John s



(No Model.)

J. S. BIRCH.

CONSTRUCTION OF VESSELS. o. 277,443. Patented May 15 1883.

' INVENTOR BY y/J4 ATTORNEY UNITED STATES PATENT OFFICE.

JOHNS. BIRCH, OF NE W YORK, NQY.

CONSTRUCTION OF VESSELS.

SPECIFICATION forming part of Letters Patent No. 277,443, dated May 15,1883. Application filed May 15, 1882. (No model.)

To all whom it may concern:

Be it known that 1, JOHN S. BIRCH, of the city, county, and State of NewYork, have invented a new and useful Improvement in Saillog-Vessels, ofwhich the following is a specification.

My improvement in sailing-vessels consists of a concave form of thebottom of the hull, the concavity beginning at a point near where thebow merges in the bottom, the bow being proportionatelylessin theperpendicular measurement to the bottom than in the common construction,and forming nearly a flat transverse section at the said point where theconcavity begins. From the bow the-concavity extends to a point where itvanishes in the stern a little beyond where the rise of the sternbegins, the bow and stern being practically the same as in ordinaryvessels, except as to the height of the perpendiculars, and theconcavity is to increase in breadth from stem to stern, also in depth.At the same time it is preferred to increase the beam of the vesselabout in the proportion that the bottom is lessened, or thereabout,making the cross-section the same; or it may be greater with goodresults. The objects are to effect better and easier passage of thevessel through the water by the removal of that angular portion of thebottom below the main part, and substituting a channel of the formdescribed, along which the water will find freer escape from thefore'quarter of the vessel when leaning abeam, and also to enable thatpart of the bottom on which the vessel rides when so leaning to be morelike the natural bottom, instead of the side on which the vessels of thecommon form mainly rest in such cases, which enables the vessel to partthe waves striking the quarter, and to ride over them easier and muchfaster than the vessels of ordinary form can do. The said constructionalso makes the vessel stiffer against the side pressure of the wind, and

therefore more comfortable to the passengers as well as safer, and itaffords the advantages of a fiat-bottom vessel when sailing erect, allas hereinafter described,reference being made to the accompanyingdrawings, in which- Figure 1 is a side elevation of a vessel of myimproved construction. Fig. 2 is a transverse section on thelinew 00.Fig. 3 is a transverse section on line 3/ y. Fig. 4 is a transversesection on line 2 z; and Fig. 5 is an elevation of the bow of thevessel, showing the manner in which it rides on the water when 5 tiltedabeam. The dotted lines in this figure, represen tingthe ordinary formof bottom, show that by the removal of the portion of the bottom withinsaid lines the buoyancy of the windward sides is diminished, and at thesame time the two sides of theimmersed section are made nearly uniform,whereby the vessel will carry more sail and ride better.

a, Figs. 3 and 5, represents the form of-the bottom of the vessel at themiddle cross-sec- 6 5 tion, y. b, Fig. 2, and c, Fig. 4, represent theform of the bottom at the fore and aft extremities of the groove of thebottom, respectively.

The dotted line d, Fig. 1, indicates the line of the bottom of thegroove from a: to z, paral- 7o lel with the keel e, the keel being madea little lower than said bottom; but 1 also intend to make the keeldeeper, if desired, and may extend it even with the bottom atf; or I mayuse a center-board, the keel being as herein shown.

It represents the water-line.

Figs. 2, 3, and 4 show the widening of the groove from bow tostern, andsaid figures, and also Fig. 1, show the increasing depth.

The advantages of the improved form of bottom which I propose forsailing diagonally to the wind are apparent in Fig. 5, which shows thatwhen the vessel is careened it rides the water substantially the same aswhen up- '85 right -that is to say, the center of gravity issubstantially over the center of the bottom on which the vessel rides,and the immersed section is substantially the same form on both sides,whereby the water divides at the forego quarter about as evenly and thevessel rides as naturally as when upright, and it will be apparent thatby increasing the breadth proportionately as the bottom isdiminished-the vessel will be much less liable to capsize.

Besides the increasing breadth and depth of the groove in the bottom ofthehull, my inven tion is distinguished from vessels of the catamaranform, and also from life-boats of double bottom, by the concave form ofthe groove, by which the change of form where the two sides of thegroove unite is more gradual and easy than in the forms above mentioned,which is more favorable to speed. Besides, it avoids the tendency of thewater to hold the vessel down bow merges in the bottom and wideningthere by suction,when risingon thewaves,thatdeeper from rearward, thebow and the stern being grooves produce. practically the'same as inordinary vessels, ex- Having thus described my invention, what I cept inthe height of the perpendiculars, sub- 5 claim, and desire to secure byLetters Patent, sta-ntially as described.

The hull of a sailing-vessel having a concave JOHN BIRCH form of thebottom, together with the keel eX- Witnesses: tensions of the bow andstern, the said con- W. J. MORGAN,

1o cavity beginning at a point near where the S. H. MORGAN.

